The present invention is directed to a portable traction device powered by a pneumatic cylinder.
Traction is widely used to relieve pressure on inflamed or enlarged nerves. While traction is applicable to any part of the body, cervical and lumbar or spinal traction are the most common. When correctly performed, spinal traction can cause distraction or separation of the vertebral bodies, a combination of distraction and gliding of the facet joints, tensing of the ligamentous structures of the spinal segment, widening of the intervertebral foramen, straightening of spinal curvature and stretching of the spinal musculature. Depending on the injury being treated, the traction component of physical therapy may require multiple sessions per week for a prolonged period of time.
Cervical traction requires a traction force up to approximately 222 N (50 lbs.). Lumbar traction typically requires force equal to half of the patient""s bodyweight, or about 333-667 N (75-150 lbs.). The equipment necessary for performing traction, however, has typically been expensive and thus only available to a patient in a therapist""s office.
Attempts to create a sufficiently low cost portable traction device for home use have thus far produced unsatisfactory results. A number of portable traction devices utilize pneumatic or hydraulic cylinders to create the traction force. Hydraulic cylinders have the disadvantage of the weight of the hydraulic fluid. Pneumatic cylinders with low pressure inputs typically can not maintain an adequate traction force for a sufficient period of time to be effective in a traction device. In an attempt to overcome this deficiency, some of these devices utilize an automatic pumping device triggered by a pressure sensing device to supply additional compressed air so that a constant level of traction force is maintained. These pump and sensor configurations add cost, weight and complexity to the traction device.
The air input pumps used on some traction devices also exhibit a number of shortcomings. For example, bulb-type air pumps produce relatively small input pressures. A small female patient can generate only about 483 kPa (7 psi) of pressure using a bulb-type pump. Consequently, small input pressure devices require large diameter cylinders to generate the necessary output traction forces. Larger diameter cylinders, when used with low pressure input devices, are more prone to leak, thereby further complicating the problem of maintaining a constant traction force for a prolonged period of time.
Therefore, what is needed is a low cost, light weight portable traction device utilizing a pneumatic cylinder which can maintain a traction force of an adequate magnitude for a prolonged period of time.
The present invention is directed to a portable traction device powered by a pneumatic cylinder. The present invention is also directed to a pneumatic cylinder suitable for use in traction devices.
The portable traction device includes a support structure having a longitudinal axis and a carriage slidable along a portion of the support structure parallel to the longitudinal axis. The carriage including restraining mechanism for releasably restraining a portion of a patient""s body to the carriage. A pneumatic cylinder includes a cylinder housing attached to the support structure. The cylinder housing contains a piston and piston rod. The piston rod is attached to the carriage for moving the carriage along the longitudinal axis relative to the support structure when pressurized air is injected into the pneumatic cylinder. The piston has at least one pressure activated seal extending circumferentially around the piston for engagement with an inside surface of the cylinder housing. A bicycle-style hand pump fluidly connected to the pneumatic cylinder is provided for injecting pressurized air into the cylinder.
In one embodiment, the portable traction device is configured for use as a portable, cervical traction device. The carriage may include a head support pad to receive a patient""s head and a pair of opposing neck supports contoured and arranged to engage the occipital area of the patient""s head when the head is on the head support pad. The neck supports are adjustably attached to the carriage to permit adjustment of the lateral separation therebetween. A head support strap may be provided for restraining the patient""s head to the support pad.
In an alternate embodiment, the portable traction device is configured as a portable, lumbar traction device. The restraining mechanism may include a waist belt for releasably restraining the lower body of the user to the carriage. The support structure preferably includes counter traction restraining mechanism for restraining the upper body of the user to the support structure. Alternatively, the restraining mechanism includes a pair of opposing, laterally adjustable hip gripping supports arranged to engage the superior edge of the user""s pelvis.
The piston has a diameter smaller than an internal diameter of the cylinder housing so that a gap is formed therebetween. The pressure activated seal may be a pair of pressure activated seals arranged circumferentially around the piston. The pressure activated seal is a generally V-shaped seal member arranged to expand when the air pressure in the pneumatic cylinder exceeds 13.8 kPa (2 psi). In one embodiment, the pressure activated seal maintains a generally static traction force of greater than 111 N (25 pounds) for a period in excess of 10 minutes without additional pressurized air being injected into the cylinder. In an alternate embodiment, the pressure activated seal maintains a generally static traction force of greater than 200 N (45 pounds) for a period in excess of 20 minutes without additional pressurized air being injected into the cylinder.
The hand pump preferably includes a gauge indicating traction force and a pressure relief mechanism to manually release pressure in the pneumatic cylinder. In one embodiment, the operator rotates the gauge relative to the hand pump to release pressure from the cylinder. The cylinder preferably includes a pressure regulator to prevent the pressure in the pneumatic cylinder from exceeding a predetermined value. Alternatively, the pressure regulator may be located on the hand pump. The hand pump is capable of injecting at least 207 kPa (30 psi) of pressure to the pneumatic cylinder.
The present invention is also directed to the pneumatic cylinder and hand pump discussed above for use as the traction force generating apparatus on a portable traction device.